Images

Alluvium visible in Salt River, Arizona (Photo by Sharon Reynolds, Arizona State University)

Illustration of Isaac Newton sitting under an apple tree, a reference to the well-known story of the epiphany Newton had when an apple fell on his head and lead to him discovering gravity.

Geodesy is the science of determining the size and shape of the earth and the precise location of points on its surface.

The geologic time scale showing each eon, era, period, epoch, and their associated ages.

Photo of Zion Canyon located in Zion National Park in Utah, United States. (Image courtesy of Justin Gould)

Photo of the Grand Canyon located in Grand Canyon National Park, Arizona, Untied States.

Photo of GPS site with instrument on a tripod and a solar panel. (Photo by John Galetzka, U.S. Geological Survey)

Photo of bridge.  Geotechnical means referring to the use of scientific methods and engineering principles to acquire, interpret, and apply knowledge of earth materials for solving engineering problems.  

Horst and graben diagram. A graben is a down-dropped block of the earth's crust resulting from extension, or pulling, of the crust. 

Diagram of great circle. The shortest path between two points on the surface of a sphere lies along a great circle.

Plot showing least squares fit. When plotting data points on a graph, the least-squares-fit is the line or curve that comes closest to going through all the points.

Diagram of left-lateral motion on fault. If you were to stand on the fault and look along its length, this is a type of strike-slip fault where the left block moves toward you and the right block moves away. See also right-lateral. 

Photo of a leaning transmission tower being held up by lifelines. Lifelines are structures that are important or critical for a community to function, such as roadways, pipelines, powerlines, sewers, communications, and port facilities.

Sand ejected through a crack forming a series of sand boils along the railroad tracks adjacent to Deschutes Parkway in Olympia. 

Lithologic cross-section example with descriptions of lithology at different depths. 

Diagram of a locked fault showing the shortening and uplift at a coastline. A locked fault is a fault that is not slipping because frictional resistance on the fault is greater than the shear stress across the fault (it is stuck).

A Love wave is a surface wave having a horizontal motion that is transverse (or perpendicular) to the direction the wave is traveling.

A magnetic polarity reversal is a change of the earth's magnetic field to the opposite polarity. This has occurred at irregular intervals during geologic time. Polarity reversals can be preserved in sequences of magnetized rocks and compared with standard polarity-change time scales to estimate geologic ages of the rocks.

Compare the fault area of the magnitude 7.3 (top) with that of the magnitude 5.6 (smallest one near the bottom).

The Landers fault (red lines at left) and the Hector Mine fault and its aftershocks (red lines and circles at right). The Hector Mine earthquake was a magnitude 7.1, and it produced thousands of aftershocks.

Liquefaction potential map of the San Francisco Bay Area, California. (Image courtesy of the Association of Bay Area Governments-ABAG)